Hydraulically controlled variable pitch propeller



H. OBRIST HYDRAULICALLY CONTROLLED VARIABLE PITCH PROPELLER 3 Sheets-Sheet l Sept. 19, 1950 Filed July 11, 1945 H. OBRIST Sept. 19, 1950 HYDRAULICALLY CONTROLLED VARIABLE PITCH PROPELLER Filed July 1l, 1945 3 Sheets-Sheet 2 hm mm mm Aawu W 7 H. OBRIST Sept. 19, 1950 HYDRAULICALLY CONTROLLED VARIABLE PITCH PROPELLER Filed July 11, 1945 3 Sheets-Sheet 5 31 lnv zntar Hzinrich Obrisl: 59 (9,0 3; ,4

Attorncgs Patented Sept. 19, 1950 HYDRAULICALLY CONTROLLED VARIABLE PITCH PROPELLER Heinrich Obrist, Zurich, Switzerland, assignor to Escher Wyss Maschinenfabriken Aktiengesellschaft, Zurich, Switzerland, a corporation of Switzerland Application July 11, 1945, Serial No. 604,476

a In Switzerland August 5, 1944 8 Claims.

This. invention relates to means for hydraulically controlling variable pitch propellers, particularly those for ships. The object of the invention is to provide means of this kind in which thehydraulic pitch-varyin pressure can be obtained by means-which, while being of a type of construction which is simple and reliable in action are entirely built into the propeller shaft. According to the present invention this is rendered possible by the fact that the casing of a servo-motor, which has a stationary piston, moves under the action of a liquid under pressure thereby effecting variation of the pitch of the propeller blades and is arranged in a portion of the propeller shaft which is constructed to form a cylinder, and that a pump which supplies the liquid under pressure required for shifting the servo-motor casing is arranged in the I an electromotor arranged within said shaft and adapted to rotate therewith. The pump which delivers the liquid under pressure may, in this type of construction, be built into the fixed or stationary servo-motor piston.

A constructional example of the subject matter of the invention is shown in a simplified mode of representation in the accompanying drawings in which:

Figs. la and lb show the two halves of the axial longitudinal section through an arrangement for hydraulically varying the pitch of a propeller for propulsing a ship, the propeller being shown in elevation. In these figures the section is taken through the servo-motor on the line II .of Fig. 2 and certain parts have been turned downwards in the plane of the drawing for the sake of clearness.

Fig. 2 shows on a larger scale a section on the line IIII of Fig. lb through the servo-motor,

Fig. 3 is a section on the line III-III through a part of Fig. 2 and Fig. 4 shows on a larger scale a section on the line IV--IV of Fig. lb.

' In the drawings, l denotes a propeller fitted with blades the pitch of which is to be varied and which serves to drive a ship. This propeller is operatively connected through a hollow shaft 2, a cover 3 which forms a whole with the latter, a part 4 constructed to form a cylinder and closed on the left hand side by said cover 3, and a further cylinder 5, to a driving shaft H, the parts 2, 3, 4, 5 and II being rigidly connected so as to rotate as a. unit. The hollow shaft 2, the cover 3 and the cylinders 4, 5 form together what is termed in this specification the propeller shaft.

The cylinder 6 of a servo-motor is arranged in.

the cylindrical part 4 in such a way that it Will slide therein. The piston of this servo-motor comprises a piston body 6 proper andla second; part 6 connected thereto by studs, as shown. This latter is connected by means of an exten-. sion 9 to a cover H] which is clamped between the cylinders 4 and 5 in such a way that the piston 6 ii is prevented from making any axialmovement. At its right hand end the servo,- motor cylinder 6 is closed by a cover 6 The reference l5 denotes an adjusting spindle which is rigidly connected to the cylinder 6 of the servomotor. The adjusting spindle I5 is coupled to a rod [6 which in its turn is connected mechanically to a mechanism M for varying the pitch of the blades of the propeller l. The two spaces on either side of the servo-motor piston 6 t are denoted by l and 8. These spaces 7 and 3 and the hollow space 4 in the cylindrical part 4 of the propeller shaft, which is not taken up by the servo-motor, are filled with a liquid, prefer ably oil. A pressure considerably above atmospheric pressure prevails temporarily in the spaces "1 and 8 during the occurrence of the adjustment of the blades, while in the space 4 prevails at all times a, pressure which is only slightly greater than the atmospheric pressure.

In the parts 6 li of the piston is mounted a toothed wheel it! which cooperates with a second toothed wheel l3. These two wheels I? and i3 constitute a pump which is driven through a shaft [1 and a toothed coupling l8 by an electromotor l9. This latter is arranged within the cylinder 5 of the propeller shaft, and is fast therein and rotates with it. For sealing the shaft ii at the right hand end of the extension 9 a sealing device is provided which comprises two sealing rings ll and a spring I'l the latter tending to force these rings against sealing seats. This sealing device is the only sealing means Working under a pressure above atmospheric pressure that has to be provided on the side at which the energy needed for the adjustment of the blades is supplied. The embodiment described also realizes the advantage that the diameter of said sealing device I1 I1 can be relatively small and that this device is exposed to a pressure above atmospheric only during the occurence of a pitch variation. Thus, the sealing problem on the side at which the supply of energy takes place is solved in a manner which ensures a minimum of oil losses.

20 denotes an intermediate member which is clamped fast between the cover 3 and the cylinaseaoss der 4, and 2| denotes a toothed wheel arranged within the cover 3, this toothed wheel 2| being operatively connected by means of a quick-pitch multiple screw thread with the adjusting spindle l5 and held in its axial position by bearings 22, 23. The intermediate member 29 has a cylindrical extension 26 in which a piston 24 compelled to rotate with the members is slidably arranged. This piston 24 is acted upon by a helical spring 21 tending to urge it towards its left hand terminal position, in which it then holds fast the toothed wheel 2! by means of a locking member 25 rigidly connected to the piston 24. In the left hand end of the cover 3 is mounted a sleeve 2% provided with a bore of square section and with an extension 26 a portion of the latter being screw-threaded. In case or necessity the position of the blades of the propeller i can be varied whilst the latter is at a standstill by rotating said sleeve 26 by hand. Any such rotation involves a throwing out ofthe locking member 25, which is in operative connection with a nut 26 co-operating with the screw-threaded por tion of said extension 26 of the sleeve 26. As

soon as the member 25 has been thrown out of 1"."

from outside in order to rotate the toothed wheel 2| meshing with said rim 28. The wheel 2i then operates the adjusting spindle l5 connected to the mechanism M for varying the pitch of the propeller blade. 33 denotes a pipe rigidly connected to the s'ervoinotor piston part 6 (Fig. 3) and communicating through a slot 34 (Fig. 1b) with the space 1 on the left hand side of the servomotor '6, 6 6 '3 This pipe 33 is connected through a second slot 34 (Figs. 3 and 4) with a passagett, which opens into a space 36. pipe 33 surrounds a pipe 30 which, as shown in Fig. '3. is rigidly connected to this pipe 33 and communicates with a groove 3i in the part B of the 'servomo'tor piston, this groove 3! communieating "in its turn with two recesses or cavities 32', 32 (Figs. 3 and L). The pipe 30 opens at left end into a space connected through a duct 30 (Fig. 1b) with a pressure space 30 allotted 'to the p'isto'n 2.4. -As is shown in Fig. 2', the pipe 33 has symmetrically opposite a second pipe '33 communicating through a slot, which corresponds to the above mentioned slot 34 and is therefore not shown in the drawings, with the space 4 'on the left hand side of the servomotor 6, 6 6 ,15 Twomovable piston valves 31 and 38 (Fig. '2) are arranged within the space 36, each of which has an opening 3'7 and 38 respectively. Aspring ifi arranged between these piston valves 13! and 38 tends to move them away from each other. The piston valve 31 controls the communication between the space 36 and a passage 4|. This lattercommunicates with a passage '42 which opens into the servomotor space '8. The piston valve 38 controls in its turn the communication between the space 38 and a passage 43 (Figs. 2 and 3), "which communicates with a passage 44 opening into the servomotor space 1. '45and 4B (Figss2 and 4) denote two spaces pro- 'vided in the part 6 of the servomotor and which fulfill temporarily the functions of a suctionor pressure space according to the direction in which the pump toothed wheels l2, l3 rotate. Communication between the interior of the pipe- 33 and the space 45 is controlled bya flap valve '4? and communication between the interior of The the pipes 33 and the space 46 is controlled by a flap valve 48. 49 and 50 (Fig. 2) denote springloaded excess pressure valves, which when they lift, enable liquid under pressure to pass through bores BI and 52 (Fig. l) in that of the spaces 8 and K respectively in which at the inoment no pressure above atmospheric pressure prevails.

53 (Fig. 1b) denotes a resistance coil against which bears a sliding contact 54 rigidly connected to the cover of the servomotor by means of a rod 54 The sliding contact 54 is thus compelled to efiect the same movements as the casing 6 of the servomotor. The coil 53 is connected by electric conductors to slip rings 58 and 5? and the sliding contact 54 is connected to a slip ring 55. The references 58 and 58 denote two further slip rings, which, together with the slip ring 56 permit current to be supplied from a mainrr, 1 z to the electromotor i9. 59 denotes a brush carrier, which permits of connection being established between the revolving and the stationary parts of the electrical arrangement, said brush carrier being also connected electrically to a controlling switch Bl provided with a handle Eli. The arrangement is such that when the handle (it? is moved towards the right, the electromotor it runs in the opposite direction to that in which it runs when the handle is moved towards the left. The direction of rotation of the electromotor [9 also determines the-direction of the pump wheels i2 and [3. Finally 62 denotes an indicating instrument, which is acted upon indirectly by the resistance coil '53 and furnishes information as to the particular position of the propeller blades at the moment. In addition to this electrical position-indicating arrangement a mechanical indicating arrangement, to which parts 10 and ll belong, also provided.

The way in which. the arrangement for hydraulically varying the pitch of the blades of the propeller works is as follows:

Assuming that the controlling switch G l has been moved into such a position that the electromotor 59 rotates the a-mp wheels l 2, 13 ii: thedire'ctio'nindicated-by the arrows in Fig. 2, the space 45 will 'act'as a suction space and the space ifi "as a force or delivery space. The suctiona-l action set up in the space 45 causes the flap valve t? to lift, so that cominunicatidn between the interior-of the pipe 33 and the suction spac'e 45-15 established. The result or this is that the pump 12, draws 'oil through the slot 34 out of the space 4 on the left hand side bf the se'rv'omo'tor 6, 3 The liquid under pressure delivered by the pump l2, 53 into the space 46 passes through a passage '63 (Fig. '2) to the right hand end face of the piston valve 3 1-, so that this latter is pushed towards the left. Oil under pressure passes into an annular groove 27 and ii-om the latter through the recess 555i and groove 3! into the pipe 30, and consequently into the pressure space 351 allotted to the piston =24, so that the latter. is pushed towards the ri 3,116 thereby causes the releasing of-thetoothed'wheel 21 which can now be rotated. the pump pressure continues to increase, the piston valve 3-1 will be pushed still -f-urthe'r to the left so that it finally establish-es communication between the passage 53 and the passage 45, with the result that oil under pressure .passes'out of the space "45 into thelpass'age 42*and, thence into the space 8 within the servomotor. Tliis'causes the 's'ervomoto'r casing to move towards the right, theadjusting spindle it: also beingcarried along with it. lhe result of all this is-that-theblades of the-propeller I will have their pitch varied by a definite amountin one direction. n the above mentioned movement of the servomotor casing 6 towards the right the oil contained in the space I will be forced through the passage 44 and the passage 43 and through the opening 38 into the space 36, out of which it can run off through the passage 35 and the slot 3& into the pipe 33, to be either drawn in again by the pump l2, I3 or allowed to run off through the slot 34 into the space 4 on the left hand side of the servomotor 6, 6 6 6 When the desired variation in the pitch of the blades of the propeller has been effected, the controlling switch 6! is moved back into its neutral position, whereupon the pump l2, l3 ceases to deliver. The spring 21 is now in a position in which it can move the piston 24 towards the left so that the wheel 2! is locked again and the propeller blades consequently secured in their new position.

When the controlling switch BI is moved over into the opposite position the servomotor cylinder 6 can be moved towards the left and a change in the pitch of the propeller blades is effected in a direction opposite to that mentioned above. In this case the annular groove 38 and the passage G3 fulfill the same functions as the groove 31 and the passage 63 fulfilled in the previous case.

Should the pump fail to act for any reason or should a breakdown'in the supply of current occur, the arrangement described makes it possible to bring the blades of the propeller into any desired position by hand after the arrangement has been stopped for a short time. As soon as this is the case, the sleeve 26 is turned by a ratchet key in such away that the locking device '25 on the piston 24 is brought out of the position in which it locks the toothed wheel 2|. By means of the same ratchet key the shaft 2:} and with it the toothed wheels 28 and 2| can be turned to the extent required for bringing the blades of the propeller into the exact position desired.

The amount by which the pitch of the blades of the propeller I has been varied can be ascertained at any time by reference to the indications furnished by the indicating instrument 62. When the itch of the blades of the propeller is effected by hand, the arrangement 10, H may conveniently be used for ascertaining the position of the propeller blades. This latter arrange-- ment also enables the electrical position indicating instrument 62 to be controlled at the same time.

For, the sake of completeness it may be mentioned that (i l and 6& denote two oil supply casings of which the casing 64 communicates through a pipe 65 with an oil storage chamber 66, so that the oil pressure prevailing in the interior of the propeller hub is always greater than the pressure which the water exerts from the outside. The casing 64 is also connected with an oil storage chamber, which however has not been illustrated so that all parts within the hub and the hollow shaft of the propeller are continuously subjected to an oil pressure of a certain magnitude.

The invention may also be used in connection withsscrew propellers which are used to drive aircraft;

What is claimed is:

1. A self-contained adjusting assembly for interposition as a unit between two coaxial rotary shafts, one of which drives the other and one of which includes an internal axially shiftable adjusting member, said unit comprising, a generally cylindrical housing having at its opposite endsrmeansfor torque-transmitting connection to respective ones of said alined shafts; means subdividing said housing into a sump and a motor chamber; a double-acting expansible chamber hydraulic motor in said sump said motor having two opposed working spaces and means for connection with said axially shiftable adjusting member; a reversible pump; pressure operated valve-means biased to a position in which they connect said two'working spaces with said sump, said valve means serving selectively in response to pressures developed by reverse operations of said pump, to. isolate respective working spaces of the motor and subject the isolated working space to the pressure so developed; a reversible electromotor in said motor chamber connected to drive said pump; releas able means biased to lock said hydraulic motor; and means serving to releasesaid locking means upon o'perationof said electromotor in either direction. i v

2. The combination defined in claim 1 in which the pump is located in the sump, the connection between said electromotor and pump passes through said subdividing means and makes a liquid-sealed joint therewith, the means for connection of the hydraulic motor with said axially shiftable adjusting member comprises a shaft which extends .through the sump and thence through a packed bearing. to the adjusting member, and means are provided to maintain the sump under a moderate hydraulic pressure.

3. The combination defined in claim 1 in which the double-acting motor comprises a fixed piston and an axially. slidable cylinder having means for direct connection to the-axially shiftable adjusting member, the pump and pressure operatedvalve means are mounted in the piston, and the piston is sustained by said subdividing means.

4. A self-contained adjusting assembly for interposition as a unit between two coxial rotary shafts, one of which drives the other and one of which includes an internal axially shiftable adjustingmember, said unit comprising, a generally cylindrical housing having at its opposite ends means for torque-transmittin connection to respective ones of said alined shafts; means subdividing said housing into a sump and a motor chamber; a double-acting expansible chamber hydraulic motor in said sump and arranged for connection with said axially shiftablc adjusting member; a reversible pump with automatic reversing valve means arranged to draw liquid from said sump and deliver it under elevated pressureselectively to one or the other working space of" said double-acting motor ac-- cording .tothe direction in which the pump is drivenpa reversible electromotor in said motor chamber and connected to drive said pump; engageable meansfor locking said hydraulic motor againstmotion; means biasing said locking means to engaged position; and pressure operated means responsive to the elevated pressure developed by operation'of said pump in either direction and serving to disengage said locking means. 2

5. A self-contained adjusting assembly for interposition as a unit between two coaxial rotary shafts, one; of which drives the other and oneof which includes an internal axially shiftable adjusting member, said unit comprising, a generally cylindrical housing having at its opposite ends means for torque-transmitting connection to respective ones of said alined shafts; means subdividing said housing into a sump and a motor chamber; a double-acting expansible chamber hydraulic motor in said sump and arranged for connection with said axially shiftable adjusting member; a reversible pump with automatic reversing valve means arranged to draw liquid from said sum-p and deliver it under elevated pressure selectively to one or the other working space of said double-acting motor ac.- cording to the direction. inv which the pump is driven; a reversible electromotor in said motor chamber and connected to drive said pump; a. rotary member arranged to be rotated by the hydraulic motor; a clutch engageable to lock said rotary member against rotation; yielding. means urging said clutch to engaging position; and pressure operated means responsive to the elevated pressure developed by operation. of said pump in either direction to disengage said clutch,

6. A self-contained adjusting assembly for interposition as a unit. between two coaxial rotary shafts, one of which drives the other and one of which includes an internal axially shiftable adjusting member, said unit comprising, a generally cylindrical housing having at its opp.r site ends means for torque-transmitting connection to respective ones of said, alined shafts; means subdividing said housing into a sump and a motor chamber; a double-acting expansible.

chamber hydraulic motor in said sump and ar. ranged for connection with said axially shiftable adjusting member; a reversible pump with automatic reversing valve means arranged to draw liquid from said sump and deliver it under elevated pressure selectively to one or the other working space of said double-acting motor according to the directionin which the pump is driven; a reversible electrom'otor in said motor chamber and connected to drive said pump; a. gear arranged to be rotated by the hydraulic motor; a clutch engageable to lock said gear against rotation; yielding means urging said clutch to engaging position; pressure operated means responsive to the elevated pressure developed by operation of said pump in either ,di-

rection to disengage said clutch; and two means manually operable at points external to said housing when the latter is at rest, the first of which comprises mechanical means for boldin said clutch disengaged. and the second of which comprises mechanical means for rotating said gear. V

7. A self-contained adjusting assembly for in.- terposition as a unit between two coaxial rotary shafts, one of which drives the other and one of which includes an internal axially shiftable .ad-. justing member, said unit comprising, a generally cylindrical housin having at its opposite ends means for torque-transmitting connection to respective ones of said alined shafts; means subdis viding said housing into a sump and a motor chamber; a dcubleacting expansible chamber hydraulic motor in said sump and comprising a piston fixedly supported by saidsubdividing means and a double-acting cylinder slidable on said piston and its support, divided by the piston spaces with said sump, said valve means being mounted in said piston and serving selectively, in response to pressures developed by reverse operations of said pump, to isolate respective workspaces of the motor and subject the isolated working space to the pressure so developed; a re versible electromotor housed in said motor chamber and mechanically connected with said pump through said subdividin means and the related piston support; releasable means biased to lock said hydraulic motor; and means serving to release said locking means upon operation of said electromotor in either direction.

3. A sel1-contained adjusting assembly for interposition as a unit between two coaxial rotary shafts, one of which drives the other and one of which includes an internal axially shiftable adjusting member, said unit comprising, a generally cylindrical housing having at its opposite ends means for torque-transmitting connection to respective ones of said alined shafts; means subdividing said housing into a sump and a motor chamber; a double-acting expansible chamber hydraulical motor in said sump and comprising a piston fixedly supported by said subdividing means and a double-acting cylinder slidable on said DlSJCll and its support and adapted for connection with said axially shiftable adjusting member; a reversible pump with automatic reversing valves arranged to draw liquid from said sump and deliver it under elevated pressure selectively to one or the other working space of said double-acting motor according to the direction in which the pump is driven, said pump and valves being housed in said piston; a reversible electromotor housed in said motor chamber and mechanically connected with said pump through said subdividing means and the related piston support; engageable means for locking said hydraulic motor against motion; means biasing said locking means to engaged position; and pressure operated means responsive to the elevated pressure developed by operation of said pump in either direction and serving to disengage said locking means.

HEINRICH OBRIST.

REFERENKJES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,734,458 Allen Nov. 5, 1929 1,829,930 Hele-shaw et al. Nov. 3, 1931 1,877,048 Popp Sept. 13, 1932 1,894,048 Lilley Jan. 10, 1933 1,952,566 Ring Mar. 27, 1934 2,258,094 Keller Oct. 7, 1941 2,279,301 Colley et al Apr. 14, 1942 2,307,578 Fedden Jan. 5, 1943 2,353,773 Unterberg July 18, 1944 2,355,039 Eves Aug. 1, 1944 2,357,229 Seewer Aug. 29, 1944 FOREIGN PATENTS Number Country Date 587,281 Germany -1- Feb. 15, 1931 553,929 Great Britain, June 10, 1943 

